The invention relates to a supporting disk for a rotor of an open-end spinning machine comprising a hub ring made of metallic material and a support ring made of polymer material, the support ring being affixed to the outer circumferential surface of the hub ring, the inner circumferential surface of the support ring and the outer circumferential surface of the hub ring being in interlocking engagement.
Such a supporting disk is known from the German Patent DE 36 15 777 A1, which corresponds to U.S. Pat. No. 4,713,932, incorporated herein by reference. The outer circumferential surface of the support ring in that reference is constructed as a smooth, uninterrupted, essentially cylindrical bearing surface; the inner circumferential surface of the support ring in that reference has a profile by which the thickness of the support ring is reduced in the middle area as compared to the edge areas. This is said to avoid undesirably high heating in the middle region of the support ring, even during heavy stress.
In such a supporting ring, however, because the axial end faces of the hub ring and the support ring are arranged in the same radial plane, the end faces of the support ring and the hub ring are both worn by excessive turning. To be sure, if the support ring is worn out it can be chemically detached from the hub ring; however, continually replacing the worn out support ring with a new support ring is not possible because the hub ring is also continually worn, and, therefore, with an increasing number of support ring replacements, the hub ring would have an increasingly smaller width in the axial direction.